1. Field of the Invention
The present invention relates to a color processing device that controls projections and recesses on the surface of a printed material.
2. Description of the Related Art
As a device that forms an image on a sheet-shaped recording medium, there is an inkjet recording device that discharges ink droplets from a head onto a recording medium and thereby performs recording. As a method of discharging ink droplets from a head, a method of using a piezoelectric element (piezo element) that generates a mechanical distortion by the application of voltage and a method of rapidly heating and vaporizing an ink and utilizing a high pressure of bubbles produced at that time are widely utilized.
Although, as an ink used in an inkjet recording device, a dye ink using a water soluble dye as a color material is widely applied, since in recent years, it has been required that the light resistance and the water resistance of a printed material be enhanced, a pigment ink is often used.
However, while the pigment ink is excellent for light resistance and water resistance, since the particle of the pigment ink is large in diameter, the pigment ink does not penetrate into but deposits on the surface of a recording medium such as glossy paper that has a coat layer or a glossy layer on the surface and that has a small micropore diameter. FIG. 1 shows a conceptual diagram of the surface of a recording medium both in a case where the dye ink is used (FIG. 1A) and in a case where the pigment ink is used (FIG. 1B). As shown in FIG. 1A, the color material of the dye ink easily penetrates into the recording medium such that the shape of the surface of the recording medium is maintained. Hence, when incident light 101 is incident on a printed material, the reflection intensity of reflected light 102 in the direction of regular reflection is intensified.
On the other hand, the pigment ink does not penetrate into but deposits on the recording medium, thereby projections and recesses are produced on the surface of a printed material. Hence, when incident light 103 is incident on the printed material, it is diffusely reflected as reflected light 104 shown in FIG. 1B. Consequently, the image clarity (the image sharpness specified by the optical property test method on plastic (JIS K7105)) that indicates the degree of blurring of a regular reflection image of illumination reflected on the printed material is disadvantageously reduced.
Japanese Patent Laid-Open No. 2005-297212 discloses a technology in which a pass mask is controlled and ink dots discharged on a recording medium are formed into a cluster, thus the state of deposition is made uniform and the surface smoothness of a printed material is enhanced. Japanese Patent Laid-Open No. 2009-12261 discloses a technology in which the height of ink deposited on a recording medium is recorded on an individual ink basis, according to the height of ink discharged onto a target pixel, the threshold value of a dither matrix used pixels therearound is controlled and thus the surface smoothness of a printed material is enhanced.
However, in Japanese Patent Laid-Open No. 2005-297212 described above, the formation of the cluster of the ink dots disadvantageously reduces the graininess. In Japanese Patent Laid-Open No. 2009-12261, since the amount of color ink discharged is controlled in order to equalize the amount of ink deposited, the amount of ink discharged is different from the amount of ink discharged with priority given to image quality such as graininess or color emission. Consequently, the image quality of an image recorded is disadvantageously degraded.